Modification of reduced keratinous substrates with a vinyl monomer

ABSTRACT

A process for the treatment of a keratinous substrate comprising the steps of (1) reduction of the substrate and (2) contacting same with a solution of vinyl monomer and free radical liberating catalyst, step (2) being effected in the presence of a watersoluble halide.

United States Patent Anzuino [451 July 11, 1972- [54] MODIFICATION OF REDUCED KERATINOUS SUBSTRATES WITH A VINYL MONOMER [72] Inventor: Giuseppe Anzuino, Vercelli, Italy [73] Assignee: Colgate-Palmolive Company, New York,

[22] Filed: May 29,1969

[21] Appl.No.: 829,096

3,291,560 12/1966 Machellet al. ..8/l27.6X

3,437,420 4/1969 Bolinger et a1 ..8/127.5 3,472,243 10/1969 Wall et al ...424/70 3,475,114 10/1969 Bolinger et al... ..8/127.5 3,481,682 12/1969 Machell ..8/l27.6 X

Primary Examiner-Albert T. Meyers Assistant Examiner-New C. Clarke Anomey-Herbert S. Sylvester, Murray M. Grill, Norman Blumenkopf, Ronald S. Cornell, Thomas .1 Corum, Richard N. Miller and Robert L. Stone [57] ABSTRACT A process for the treatment of a keratinous substrate comprising the steps of l reduction of the substrate and (2) contacting same with a solution of vinyl monomer and free radical liberating catalyst, step (2) being effected in the presence of a water-soluble halide.

6 Claims, No Drawings MODIFICATION OF REDUCED KERA'I'INOUS SUBSTRATES WITH A VINYL MONOMER The present invention relates in general to the treatment of keratinous substrates and in particular to the provision of a novel process for the modification of the properties of keratinous substances as typified by, for example, hair, wool, etc.

As is well known, keratinous materials may be modified in terms of their chemical and/or physical properties by suitable processing, e.g., the treatment of human hair for purposes of permanent waving or other conditioning, the relevant techniques being described in the published literature both patent and otherwise. Thus, and with respect to the treatment of human hair for purposes of imparting curl thereto, conventional processing usually involves an initial hair impregnation treatment with a suitable reducing solution whereby to deposit predetermined quantities of reducing agent on the individual hair fibers. Thereafter, chemical and/or physical modification of the hair is brought about by treating the same with a suitable oxidizing solution in a known manner. The materials necessary to the implementation of such techniques are well known in the art and are available commercially in a wide variety of forms. Despite the fact that techniques of the aforedescribed type are exploited to a significant extent on a commercial scale, such methods have nevertheless been found in practice to be subject to one or more disadvantages tending to detract considerably from their commercial desirability. Perhaps, the primary objection concerns the failure of such techniques to provide a final hair set possessed of optimum form-retention stability, hygroscopicity, etc., the latter desideratum being of primary importance as regards the obtention of optimum hair flexibility devoid of undesired brittleness, hardness, etc. Other disadvantages found to characterize hair treating processes heretofore promulgated include, for example, their objectionable tendency to yield a hair product of inferior body, thickness, lustre, etc. It has been also ascertained in practice that many of the compositions necessary for use in such processing characteristically yield film deposits deficient in the requisite degree of adhesion, the final film deposit exhibiting a highly objectionable tendency to flake off, dry to a hard frangible depost and/or discolor the hair. As will be readily evident, occurrence of one or more of the foregoing shortcomings would suffice to vitiate any possibility of achieving the desired lustrous appearance.

Other disadvantages found to inhere in the use of hair conditioning compositions currently available commercially include their pronounced tendency to impair or otherwise deleteriously affect the structural integrity, i.e., strength properties of the keratin fiber per se, e.g., elastic properties, tensile strength characteristics, etc. Deficiencies in this area can well prove intolerable since their effects are invariably manifested in the form of dull, lifeless hair highly difficult to manage. ln other instances it is found that the dye receptivity characteristics of the keratinous substrate selected for treatment are seriously impaired by a given conditioning treatment. As will be understood, the ultimate requirements imposed upon a given hair conditioning treatment may vary considerably; thus, the involved treatment may be one primarily adapted to impart curl to the hair or conversely such treatment may be one designed to promote selective improvement in one or more such properties as tensile strength, elasticity, dye receptivity, body, thickness, etc. i

As a result of the foregoing, considerable industrial activity has focused upon the research and development of methods and compositions particularly and beneficially adapted for use in connection with techniques designed to enable purposive modifications in the properties of keratinous substrates including hair, wool, etc.

A multi-step procedure for the treatment of keratinous materials to achieve predetermined modifications in one or more properties of such material, is one which involves the sequential steps of (1) reduction, (2) rinsing and (3) oxidation. In accordance with the aforedescribed process, initial reduction of the keratin material is effected by treating same with a reducing solution for a time sufficient to permit substantial reduction of the keratin substrate, the term reduction here connoting the conversion of cystine linkages, i.e., disulfide bonds to mercaptan. The degree of reduction conversion can be controlled as desired by suitable choice of, for example, reducing agent, concentration, period of reducing solution-keratin contacting, etc. Upon completion of the desired extent of reduction, the keratin material is thereafter subjected to a thorough rinsing or equivalent operation for purposes of removing residual reducing agent. The utilization of an intermediate rinsing operation comprises a particularly critical phase of the over-all processing scheme since realization of the improvements contemplated depend critically thereupon. Thus, for example, complete removal of reducing agent militates against any likelihood of monomer polymerization occurring in any appreciable degree within the interstices or free space surrounding the fiber elements, the polymerization step being effectuated following completion of the rinsing operation. It is, of course, imperative to the efiicacy of such processing that the involved chronology of operations be precisely complied with in order to assure the obtention of the manifold advantages made possible thereby.

Yet another technique for effecting the modification of keratinous substrates is a method residing in the use of a specific catalyst material, namely, persulfuric acid and/or its water soluble salts. The use of this specific catalyst material obviates any necessity for the use of multi-step processing to accomplish the desired keratin modification. Thus, the desired objectives can be achieved by the use of a single processing solution containing as essential ingredients the monomer material and persulfuric catalyst.

In accordance with the discovery forming the basis of the present invention, it has been ascertained that processes of the aforedescribed type, as well as any process singularly adapted for use in the treatment of keratinous substrates and involving the use of vinyl monomer capable of undergoing free radicalinduced polymerization, may be synergistically modified to advantage by conducting the polymerization phase, i.e., monomer or oxidizing solution treatment in the presence of a promoter selected from a highly delimited class of materials such promoter serving to augment or otherwise enhance the polymer grafiing rate.

Thus, the primary object of the present invention resides in the provision of an improved process for the treatment of keratinous substances, said process providing highly effective means to achieve particular and selected variations in one or more properties characterizing said keratinous substance.

Another object of the present invention resides in the provision of an improved process for the treatment of keratinous substrates, said process being beneficially and advantageously adapted for implementation in connection with the setting, waving, or other conditioning of human hair to provide a hair product having excellent properties with respect to of form retention stability, thickness, body, lustre and the like.

A further object of the present invention resides in the provision of a process for the treatment of keratinous substrates to enhance or otherwise augment the affinity of same for various types of dyestuffs.

A still further object of the present invention resides in the provision of a process for the modification of keratinous materials and having exceptional utility as regards the treatment of fibrous materials constituted wholly or partly of wool to render the same more resistant to adverse environmental effects, e.g., moisture, heat, etc.

Still another object of the present invention resides in the provision of a process for the modification of keratinous materials, said process being characterized by making possible the realization of substantial improvement in catalyst efficiency.

Other objects and advantages of the present invention will become more apparent hereinafter as the description proceeds.

The attainment of the foregoing and related objects as made possible in accordance with the present invention which in its broader aspects includes the provision of a process for the modification of keratinous substrates, which comprises treating a keratinous substrate which has been previously treated with a reducing agent, with a solution comprising (1) a free radical liberating peroxide catalyst material capable of initiating the polymerization of ethylenically unsaturated vinyl monomer compounds and (2) a vinyl monomer containing at least one grouping ofthe formula:

said monomer being capable of undergoing free radical-induced polymerization said treatment being effected in the presence of a water-soluble halide salt, i.e., a salt of bromine, chlorine etc. with a water solubilizing cation such as alkali metal, e.g., lithium, sodium, potassium, etc.; ammonium; substituted ammonium, i.e., wherein one or more of the hydrogen atoms is replaced by alkyl, hydroxyalkyl and the like. The present invention is particularly and advantageously adapted for use in connection with a wide variety of keratin modification techniques, the sole requirement being that such technique involve as an essential manipulative step the employment of a monomer solution treatment in the presence of a free radical liberating catalyst for purposes of effecting modifications in the keratin substrate. As previously mentioned, the process described herein may be employed to significant advantage in conjunction with a process which is uniquely atypical, in that it necessarily involves the use of the keratin substrate per se as the reducing agent, which forms an effective redox couple in combination with the peroxide compound in the monomer treatment phase to yield polymerization-initiating free radical species. Thus, the initial reduction reaction is designed to bring about substantial reduction of the keratin substrate with the conversion of disulfide to mercapto. Moreover, due to the intermediate rinsing operation which comprises a critical step of the process, substantially complete removal of reducing agent per se, e.g., bisulfite, thioglycolate or the like is virtually assured. Accordingly, upon introduction of the monomer solution, initiation of the polymer-forming reaction is confined practically exclusively to the keratinous mass, the latter serving as the locus of the free-radical liberating reaction. This particular mode of proceeding provides the significant advantage that any possibility of solution" polymerization is minimized, if not completely avoided, the quoted terminology connoting that condition which arises by virtue of polymer formation occurring within the free space area or interstices of the keratinous substrate.

Although having particularly beneficial application in the aforedescribed technique, it will be understood that the process described herein may, also be utilized to pronounced advantage in keratin modification treatments wherein the reducing agent component is present as such during the monomer treating phase. With processes of the latter type, the keratin material is present in non-reduced form, i.e., with disulfide linkages intact, during the monomer treatment phase and, as such, serves solely as a carrier for the reducing agent, i.e., the initial step according to processing of this type is solely for purposes of depositing reducing agent upon the individual fibers constituting the keratin mass. It is, of course, of paramount importance when proceeding according to the aforedescribed embodiments, that anything in the nature of an intermediate rinsing step for purposes of removing reducing agent be omitted. As will be readily apparent, provision of the requisite catalytic conditions as an incident to the monomer solution treatment depends critically upon the presence of reducing agent, ie, the mutual and intimate contacting of peroxide compound and reducing agent. As is well known, disulfide linkages present in keratin-containing substances such as typified by hair, wool, etc., are readily capable of conversion to sulfhydryl or mercapto in the presence of relatively strong reducing agents such as ammonium thioglycolate. The mercapto groups, thus provided, exhibit a pronounced capability of reducing peroxide catalyst materials with the attendant, in-situ generation of free radical species the latter providing effective means for initiating vinyl monomer polymerization. As previously explained, the predominant portion of vinyl monomer polymerization initiation as well as propagation is necessarily confined to the keratin particles per se when proceeding according to the preceding technique.

In contradistinction, polymerization when effected according to the more conventional techniques, will proceed unabated both within and without the keratinous fibers per se in view of the presence of copious quantities of reducing agent.

The oxidizing solutions of the present invention comprise as essential ingredients (1) at least one vinyl type monomer, 2) a free radical liberating peroxide catalyst and (3) a water-soluble halide salt. Vinyl monomers suitable for use in the practice of the present invention encompass a relatively wide variety of materials and in general comprise any of those which are capable of undergoing free radical-induced polymerization. Monomer materials falling within the ambit of the foregoing definition may be defined as those compounds containing at least one grouping of the fonnula:

Accordingly, both mono-and poly-ethylenically unsaturated compounds are contemplated for use herein. Such monomer materials may also be represented for convenience according to the following structural formula:

wherein R represents hydrogen, lower alkyl of one to four carbon atoms, e.g., methyl, ethyl, propyl, butyl, isobutyl, etc., and R represents (a) carbalkoxy, i.e., COOR wherein R represents hydrogen, alkyl containing from one to 20 carbon atoms, e.g., methyl, ethyl, n-pentyl, octyl, lauryl, stearyl and the like; alkenyl, containing from three to 10 carbon atoms, e.g., ally], 1,2-butenyl, 2,3-butenyl, 1,2-hexenyl, 2,3-hexenyl, etc.; hydroxyalkyl containing from two to 10 carbon atoms, e.g., 2-hydroxypropyl, 3-hydroxypropyl, Z-hydroxybutyl, 2,4,dihydroxybutyl, 4,6-dihydroxy hexyl, etc. monoand dialkylaminoalkyl, each of said alkyl preferably containing from one to four carbon atoms e.g., 2-N,N-diethylaminoethyl, 2-N- t-butylaminoethyl, 2-N,N-dimethylaminoethyl, 3-N,N- diisobutylaminopropyl; haloalkyl containing from one to 10 carbon atoms, e.g., hexafiuoro-isopropyl, perfluoroethyl, perfluoropropyl, 2-difluoro, 3-trifiuoropropyl, 2-chloroethyl, 2- chloropropyl, l,1 ,9-trihydroperfluorononyl methacrylate etc., vicinal epoxyalkyl containing from three to six carbon atoms, e.g., glycidyl, 3,4-epoxybutyl, 4,5-epoxypentyl, 2,3-epoxybutyl, etc., (b) amido, including both substituted and unsubstituted forms, such group corresponding to the following structural formula:

wherein R and R represent hydrogen alkyl and preferably lower alkyl or alternatively may represent the atoms necessary to complete a polyunsaturated molecule such as:

wherein R represents an alkylene bridge containing preferably from one to four carbon atoms such as methylene,

ethylene, propylene and butylene, (c) halogen such as chlorine, bromine, etc., ((1) alkoxy, e.g., methoxy, ethoxy, cyclohexoxy, (e) cyano, i.e., the grouping C N, (f) alkenyl aryl, e.g., o, m and p The aforementioned monomer materials may also be provided in the form of their salified derivatives, e.g., salts with water solubilizing cations. Thus, in the case of acrylic acid, methacrylic acid, etc., the monomer material prior to use may be converted to a suitable salified form such as typified by calcium acrylate, i.e., (Cl-l Cl-l-COO) Ca, sodium acrylate, potassium acrylate, calcium methylacrylate, and the like.

As examples of monomer materials falling within the ambit of the foregoing definition and description there may be mentioned in particular and without necessary limitation the following:

methyl methacrylate butyl methacrylate allyl methacrylate glycidyl methacrylate methyl acrylate allyl acrylate lauryl methacrylate Z-hydroxypropyl methacrylate ethyl acrylate isobutyl methacrylate t-butyl methacrylate n-pentyl methacrylate n-hexyl methacrylate isooctyl methacrylate t-octyl methacrylate 3,4-epoxybutyl acrylate 2,3-epoxybutyl methacrylate 4,5-epoxypentyl methacrylate butyl acrylate 3,4-butenyl acrylate 4,5-pentenyl methacrylate 5,6-hexeny acrylate tridecyl methacrylate tetradecyl methacrylate cetyl methacrylate octadecyl methacrylate eicosyl methacrylate 3-hydroxypropyl acrylate 2,4-dihydroxybutyl methacrylate ethylene glycol monomethacrylate hexafluoroisopropyl acrylate hexafluoroisopropyl methacrylate perfluoroethyl acrylate 2,2, difluoropropyl methacrylate Z-t-butylaminoethyl acrylate 2-t-butylaminoethyl methacrylate Z-diethylaminoethyl acrylate Z-dimethylamino acrylate perfluoroisobutyl acrylate 2-fluoroethyl methacrylate methacrylic acid acrylic acid Z-dimethylaminoethyl methacrylate 2-( 2-diethylamino)ethyl methacrylate 1,2-propylene chloride vinyl chloride vinyl bromide vinyl fluoride N -tetriary-butyl methacrylamide N,N-diethyl methacrylamide N,N-dipropyl acrylamide N,N -methylene-bis-acrylamide N,N-ethylene-bis-( N,N-diethyl) acrylamide N,N-propylene-bis-( N,N-diisopropyl) methacrylamide acrylonitrile methyl vinyl ether propyl vinyl ether isobutyl vinyl ether methyl isopropenyl ether divinyl benzene etc.

In the case of polyfunctional monomeric materials such as typified by allyl methacrylate and divinyl benzene and the like, it will be understood that considerable crosslinking occurs in addition to the predominant graft copolymerization reaction during oxidizing treatment of the keratinous substrate. This result occurs since monomer materials of this type possess more than one group capable of reaction with reduced disulfide linkages under the reaction conditions employed. It will in addition be understood that the monomer materials contemplated for use herein may be employed singly or in admixture comprising two or more. Selection of specific monomer systems will depend primarily upon the requirements of the processor having reference to the nature of the keratin material under treatment, the specific properties desired in the ultimate product, monomer reactivity, etc.

The manner in which the polymerization reaction proceeds depends vitally upon the nature of the monomeric material employed; thus, in the case of poly-functional monomers such as typified by allyl methacrylate, divinylbenzene, etc., a significant degree of crosslinking occurs supplementary to the predominant graft copolymerization reaction. This is readily explainable by reference to the fact that polyfunctional monomer materials of this type possess more than one group capable of polymerizing under the reaction conditions employed. It will also be understood that the monomer materials contemplated for use in accordance with the present invention may be employed singly or in admixture comprising two or more. In any event selection of specific monomer systems will depend primarily upon the requirements of the processor having reference to the nature of the keratin material under treatment, the specific properties desired in the ultimate product, monomer reactivity, etc. As will be made readily evident hereinafter, such properties as dye affinity, for example, may be substantially modified by the use of monomer materials capable of yielding polymeric segments having a high population density of ionizable groups.

The catalyst materials prescribed for use in accordance with the present invention likewise encompass a relatively wide variety of substances well known in the art for such purposes. In general, catalyst compounds capable of liberating free radicals in the presence of reduced disulfide, i.e., mercaptan, are eminently suitable for use herein. As particular examples of suitable catalyst materials there may be mentioned without necessary limitation, inorganic and organic peroxides, hydroperoxides, peracids as well as their watersoluble salts with suitable representatives including, cumene hydroperoxide, tertiary-butyl peroxide, benzoyl peroxide, peracetic acid, perbenzoic acid, tertiary-butyl hydroperoxide, sodium peracetate, potassium peracetate, sodium perbenzoate, etc., potassium persulfate, sodium persulfate, persulfuric acid, and the like. The concentration of catalyst material employed is not particularly critical beyond the obvious requirement that such material be present in catalytic quantities, i.e., small but efiective amounts sufficient to initiate polymerization. Accordingly, the concentration employed may vary over a relatively wide range. In any event, optimum realization of the improvements described herein can be assured by the employment of the catalyst material in concentrations ranging from about 0.001 to 1 to about 5:1 moles/mole of monomer with a range of 1:8 to 1:2 being particularly preferred. Actually, optimum catalyst concentration will depend upon a number of factors including, for example, monomer reactivity, the temperature employed during the treatment, the nature of the keratinous material, etc. Moreover, it will be understood that departures from the ranges stated may be advisable in particular instances due to unusual or peculiar requirements.

The third critical component of the oxidizing solutions contemplated for use herein comprises the water-soluble halide. The nature of the water solubilizing cation is not particularly critical, the salient requirement with respect thereto being that such cation be devoid of any tendency to deleteriously affect the keratin substrate or its immediate environs. As particular examples of water-soluble halide found to be eminently suitable for use herein there may be mentioned, for example, lithium bromide, lithium chloride, sodium bromide, sodium chloride, potassium bromide, potassium chloride, ammonium bromide, and ammonium chloride etc. The aforementioned bromides and chlorides are uniquely characterized in their exceptional capacity to augment to a considerable extent the graft copolymerization rate obtainable. Thus, the use of the halide salt in relatively minor amounts nevertheless permits the attainment of manifold increases in the polymerization reaction rate, thereby enabling the grafting of increased quantities of polymer for a given period of treatment. The concentration of halide employed may likewise vary within relatively wide limits. In any event, it will usually be found that beyond certain concentration values incremental increases in the amount of halide employed fail to give rise to corresponding increases in graft polymerization rate, i.e., the quantum efficiency of the halide compound tends to diminish with the use of increased concentrations thereof. In any event, significant enhancement in polymer grafting rate can be obtained by the use of the halide salt in concentrations ranging from about 0.025 to about 40 moles/mole of monomer with a range of 4 to 10 found to be particularly beneficial. Apparently, the halide ion contributes effectively to the reaction mechanism giving rise to the formation and proliferation of free radicals. Thus, the halide salt, e. g., lithium bromide, appears to react with the peroxide catalyst material, e. g., potassium persulfate, resulting in the liberation of free radical species according to the following sequence of reactions,

In the presence of reduced keratin fibers, e.g., wool, chain transfer can take place, the reaction involved being represented as follows:

Experimental evidence likewise suggests that the exceptional improvement in graft copolymerization rate cannot be explained solely by reference to the foregoing. Apparently, the presence of the halide compound promotes swelling of the keratin mass, e.g., fibers, while favoring the absorption of peroxide catalyst and monomer according to concentration effects.

The respective monomer, catalyst and halide salt ingredients are preferably provided in the form of a homogenously dispersed medium employing one or more solvent materials of an inert nature. Thus, such ingredients may be formulated utilizing simple aqueous solutions or altematively solvent or mixed solvent systems, the nature and proportions of solvent employed depending, inter alia, upon the solubility characteristics of the monomer component. With respect to mixed solvent systems, beneficial results are readily obtainable with the use of co-solvent mixtures consisting of from about 10 to about 90 percent by weight water, the remainder comprising one or more water miscible organic solvents, such as lower alkanol, e.g., ethanol, n-propanol, isopropanol, etc.; ketone, e.g., acetone; glycols, e.g., ethylene glycol, propylene glycol, etc.; ethers; ether glycols, e.g., ethylene glycol monomethyl ether, etc.

The efficiency of the subject process depends to a great extent upon the temperature employed during the monomer solution treatment. Thus, it is found that the use of elevated temperatures is mandatory in order to obtain polymer grafting rate consonant with efficacious commercial practice. In general, it is found that optimum results are obtainable with the use of temperatures falling within the range of from about 90 to about 200F. with a range of 100 to 140F. being especially preferred. Again departures from the aforestated ranges may be dictated in a particular circumstance depending to a great extent upon the nature of the keratin substrate being subjected to treatment. Accordingly, the treatment of wool as to be distinguished from, for example, on-scalp hair treatments correspondingly permits considerably more latitude as regards the selection of temperature. In any event, optimum temperature values for the problem at hand having reference to the volatility of the solution medium, decomposition points of the various reagants and reactants, etc. can be readily determined by those having reasonable skill in the art.

The following examples are given for purposes of illustration only and should not be considered in any way as necessarily imposing a limitation on the present invention. All parts and percentages given are by weight unless otherwise indicated.

As previously mentioned, increasing the concentration of water-soluble halide salt in the monomer solution leads to increased polymer grafting rates, the observed increases becoming, however, less pronounced within the higher concentration ranges. This situation is demonstrated by reference to the following examples in which the keratin sample selected for treatment comprises human hair, each sample weighing 1 i 0.003 gm. In each instance the hair sample is subjected to a reduction treatment for a period of 15 minutes utilizing an aqueous solution of ammonium thioglycolate (6 percent) having a pH of 9. Upon completion of the reduction treatment, the hair sample is rinsed thoroughly so as to remove residual reducing agent. Thereafter, the reduced hair sample is treated with a monomer solution of specified composition for a period of one hour at a temperature of 105F. Approximately 27 ml of monomer solution is employed per gram of hair treated. The amount of grafted polymer is calculated as the percent dry weight increase after drying for 12 hours over calcium chloride in a dry box. The results obtained are summarized in Table 1.

As the above-summarized data clearly indicates, marked increases in polymer grafting accompany the use of the bromide salt in accordance with the present invention when compared to control sampling omitting the bromide. Thus, the addition of 7.4 percent by weight of lithium bromide to a monomer solution comprising 1.85 percent methyl methacrylate, 0.37 percent potassium persulfate, 19.0 percent ethylene glycol monomethyl ether with the balance water, gives rise to an increase in percent grafting in excess of percent. However, as will be noted, within the higher concentration ranges, i.e., concentrations approximating 20 percent, increases in the bromide concentration far exceed the corresponding increase in polymer grafting. Thus, synergistic effects upon catalyst efficiency made possible by the use of the bromide compound tend to diminish somewhat in the higher concentration ranges.

As illustrated in the following examples, increasing the amount of monomer employed serves to increase the amount of polymer grafted. In each instance, the procedure described in connection with Examples l-6 is followed.

TABLE 2 As would be expected, increasing the concentration of monomer employed in the treating solution leads to significant increases in the amount of polymer grafted. The difference in the respective concentrations of monomer and/or catalyst in the external solution and internal solution, the latter signifying that portion of the monomer solution which has been absorbed or otherwise imbibed into the keratinous mass, constitutes a measure of the driving force which determines to a great extend the polymer grafting rate obtainable. Accordingly, the greater such concentration difference, i.e., A C, the greater the polymer grafting rate due to the greater takeup of treating solution by the keratin mass. The concentration of the internal solution will, of course, depend critically upon the population density of available mercapto; thus, greater amounts of mercapto lead to accelerated monomer and catalyst consumption rates, this condition tending to maintain a greater A C value. However, as the treating process is continued, the number of active reduction sites decreases markedly thereby leading to substantial diminuation in monomer and catalyst consumption rates and concomitantly, A C. The monomer component(s) may be employed in a relatively wide range of concentrations subject, of course, to certain implicit limitations; thus, the concentration selected should be conducive to the obtention of efficient monomer-catalyst-keratin contacting and accordingly, the upper limiting value on concentration values should be selected having reference thereto. Moreover, economic considerations alone may well militate against the use of solutions of exceedingly high dilution. In any event, it is usually advisable to maintain a monomer concentration falling within a range of from about 1 percent to about 30 percent by weight of total solution with a range of 5 percent to percent being preferred.

A similar situation exceeds with respect to the quantity of catalyst employed, i.e., increased quantities of catalyst lead in general to greater polymer grafting rates. This is illustrated by the following examples wherein the procedure observed is that described in the foregoing examples.

As the above-summarized data would suggest, increasing the concentration of peroxide catalyst leads to significant improvement in the efiiciency of the oxide-reduction system, such improvement being manifested in terms of increased polymer grafting. As will be further noted, enhanced polymer grafting is obtainable despite the use of each of the catalyst In general, excess quantities of peroxide catalyst should be avoided, i.e., amounts substantially in excess of those hereinbefore prescribed in order to minimize any possibility of uncontrolled formation of bromine the latter comprising a powerful polymerization inhibitor.

As pointed out hereinbefore, organic solvent materials having poor precipitant properties have somewhat of a retardant effect upon the polymer grafting rate. This is illustrated in the following examples wherein the procedure observed is that described in the foregoing examples.

TABLE 4 concenconcentration tration ethylene concenmethyl concenglycol tration metharyltration monomethyl lithium Ex. late K 8 0 ether bromide percent N0. grafting The foregoing examples clearly illustrate the depressant effects upon polymer grafting attributable to the use of a poor precipitant solvent as represented by ethylene glycol monomethyl ether. However, and as will be made evident by comparison with Example 1, the employment of a monomer solution containing 37.03 percent of ethylene glycol monomethyl ether in combination with 7.40 percent lithium bromide is nevertheless capable of providing polymer grafting rates substantially in excess of those obtained with similar procedures but omitting the lithium bromide.

The foregoing examples illustrate one of the particularly valuable aspects of the present invention, namely, a plurality of means is afforded to control the polymer grafting reaction rate; thus, increased polymer grafting rates are attainable by merely increasing the quantity of catalyst, monomer, and/or halide salt. Conversely, reduced polymer grafting rates can be achieved by merely decreasing the concentration of such ingredients or alternatively, by increasing the proportion of, for example, ethylene glycol monomethyl ether or similar solvent.

Results similar to those described in the foregoing table are obtained when the procedures described therein are repeated but employing in lieu of methyl methacrylate the following:

butyl methacrylate lauryl methacrylate allyl methacrylate 4,5-pentenyl methacrylate glycidyl methacrylate 3,4-epoxybutyl methacrylate Z-hydroxypropyl methacrylate ethylene glycol monomethacrylate methacrylic acid dimethylaminoethyl methacrylate N,N-diethyl methacrylamide methacrylamide N,N-methylene-bis-acrylamide N-tertiary-butyl methacrylamide calcium acrylate methyl acrylate butyl acrylate hexafluoroisopropyl acrylate perfluoroisobutyl acrylate calcium acrylate acrylonitrile divinyl benzene In addition to lithium bromide, highly efficacious polymer and bromide components in the lower concentration ranges. grafting results are attained with the use of sodium bromide,

lithium chloride, ammonium chloride, and ammonium bromide. The bromide salts appear to be somewhat more effective in that moderately higher polymerization rates are obtainable therewith.

Moreover, similar results are obtained when the persulfate catalyst is replaced by equivalent amounts of, for example, cumene peroxide, cumene hydroperoxide, benzoyl peroxide, sodium perbenzoate, peracetic acid, tertiary-butyl hydroperoxide and tertiary-butyl peroxide. Actually, the nature of the peroxide catalyst material employed is not particularly critical apart from the requirement that such material be capable of initiating the polymerization of vinyl type monomers in the presence of mercapto groups.

Within the broad class of catalyst materials found to be suitable herein it will be found that the effectiveness of a given member may vary; in any event, deficiencies in catalyst efficiency may be compensated for where encountered by merely increasing the quantity employed, or by resorting to the other means described herein for augmenting the polymer grafting rate.

Although the foregoing examples demonstrate the efficacy of the present invention in connection with keratinous sub strates comprising human hair, it will be understood that the invention is in no wise limited thereto. Thus, similar values as regards polymer grafting are obtained when the procedures exemplified are repeated but employing in lieu of human hair such keratinous substrates as wool, and various types of animal hair. Again, the precise nature of the material selected for treatment is not of critical importance since the subject process is admirably stated for use in connection with any of a wide variety of keratin substances, the sole requirement being that functional groups either in the form of disulfide or reduced disulfide be present. Thus, the term keratinous substrate in the context of the present invention is to be so construed.

The nature of the modification effected in the keratinous substrate selected for treatment will depend, of course, to a great extent upon the monomer material selected for use. In general, it is found that such properties as equilibrium moisture content may be beneficially modified in accordance with the present invention by the utilization of, for example, methyl methacrylate monomer. The tendency of a given hair sample to retain considerable quantities of moisture is considered quite objectionable since the form retention stability of such hair sample is adversely affected thereby. Thus, it is found that the moisture-repellency properties of hair can be augmented considerably despite exposure to severe humidity environments by merely increasing the amount of the polymer material grafted. This aspect of the subject invention is illustrated by the following examples which summarize the results obtained in connection with the humidity exposure of a plurality of hair samples having the indicated amounts of polymethyl methacrylate grafted thereto.

As the above-data makes clear, the efiect of incorporating the indicated quantities of polymethyl methacrylate is the substantial reduction in the equilibrium moisture content of the treated hair samples. As is well known, the tendency of hair to absorb significant quantities of water is an undesirable attribute since the retained moisture functions to dissipate or otherwise destroy the curl or wave retention capacity of the hair. Thus, by virtue of the present invention, the ability of fibrous keratinous materials to withstand the deleterious effects of humid environments may be significantly enhanced with the concomitant advantage that the effective life of a permanent wave set is correspondingly prolonged.

In general, keratinous materials which have been exposed to environments which tend to be damaging toward same exhibit a greater tendency to undergo more favorable polymerization reactions, i.e., more accelerated grafting rates. This situation can probably be explained by reference to the fact that the damaged keratin fiber for example is of more porous structure the latter condition being more conducive to penetration of reagents into the fiber mass. Thus, with reference to human hair, for example, the term damaged within the context of the present invention would connote, for example, bleached hair, permanently waved hair, etc. Thus, it is invariably found that the adaptability of a given hair sample to the process of the present invention can be enhanced, for example, by subjecting the sample to one or more preliminary bleaching treatments with plural treatments usually leading to more favorable results.

What is claimed is:

1. A process for the modification of keratinous materials which comprises treating at a temperature of from to 200F. a keratinous substrate which has previously been treated with reducing agent and thoroughly rinsed to remove residual reducing agent, with an effective amount of a solution consisting essentially of 1. as the sole catalyst component, a free radical liberating peroxide catalyst material capable of initiating the polymerization of ethylenically unsaturated vinyl monomer compounds; 2. a vinyl monomer, containing at least one grouping of the formula:

CH =C said monomer undergoing polymerization in the presence of said peroxide catalyst, said process being effected in the presence of from 0.025 to 40 moles per mole of monomer of a water-soluble halide of an alkali metal or ammonium, the concentration of said monomer being from 1 to 30 percent by weight of the total solution, the molar ratio of said peroxide catalyst to monomer being 0.001 :1 to 5:1; and

3. an inert solvent.

2. A process according to claim 1 wherein said halide is lithium bromide.

3. A process according to claim 1 wherein said peroxide catalyst material is potassium persulfate.

4. A process according to claim 1 wherein said monomer is a compound of the following structural formula wherein R is selected from the group consisting of hydrogen and lower alkyl and R is selected from the group consisting of a. carbalkoxy of the formula -COOR wherein R is selected from the group consisting of hydrogen, alkyl containing from one to 20 carbon atoms, alkenyl containing from three to 10 carbon atoms, hydroxyalkyl containing from two to 10 carbon atoms, vicinal epoxyalkyl containing from one to carbon atoms and mono and dialkylaminoalkyl each of said alkyl containing from one to four carbon atoms and b. amido of the following structural formula wherein R and R are independently selected from the group consisting of hydrogen, lower alkyl or together represent the atoms necessary to complete a grouping of the formula 

2. A process according to claim 1 wherein said halide is lithium bromide.
 2. a vinyl monomer, containing at least one grouping of the formula: said monomer undergoing polymerization in the presence of said peroxide catalyst, said process being effected in the presence of from 0.025 to 40 moles per mole of monomer of a water-soluble halide of an alkali meTal or ammonium, the concentration of said monomer being from 1 to 30 percent by weight of the total solution, the molar ratio of said peroxide catalyst to monomer being 0.001:1 to 5:1; and
 3. an inert solvent.
 3. A process according to claim 1 wherein said peroxide catalyst material is potassium persulfate.
 4. A process according to claim 1 wherein said monomer is a compound of the following structural formula wherein R is selected from the group consisting of hydrogen and lower alkyl and R1 is selected from the group consisting of a. carbalkoxy of the formula -COOR2 wherein R2 is selected from the group consisting of hydrogen, alkyl containing from one to 20 carbon atoms, alkenyl containing from three to 10 carbon atoms, hydroxyalkyl containing from two to 10 carbon atoms, vicinal epoxyalkyl containing from one to 10 carbon atoms and mono and dialkylaminoalkyl each of said alkyl containing from one to four carbon atoms and b. amido of the following structural formula wherein R3 and R4 are independently selected from the group consisting of hydrogen, lower alkyl or together represent the atoms necessary to complete a grouping of the formula wherein R5 represents lower alkylene c. halogen d. alkoxy e. cyano and f. alkenyl aryl said alkenyl containing from one to four carbon atoms.
 5. A process according to claim 1 wherein said monomer is methyl methacrylate.
 6. A process according to claim 1 wherein said alkali metal is sodium, lithium or potassium. 